Analysis of ϱ polarization in a π−p → ππN experiment at 2.77 GeV/c

Spin density matrix elements and the corresponding multipole parameters of ϱ mesons produced in the reactions π−p → ϱon and π−p → ϱ−p obtained from a high statistics experiment at 2.77 GeV/c are computed, as functions of transfer, in the whole transfer domain. Representative points are plotted in multipole parameters space: it clearly shows the differences between ϱo and ϱ− mesons, and allows first an immediate test of the positivity conditions, and further a complete and easy confrontation to predictions of various models.